Drosophila myosin V has a strikingly different motor mechanism from that of vertebrate myosin Va and it is a non-processive, ensemble motor. We have generated a polyclonal antibody to the coil-coiled domain of myosin V and have been localizing myosin V in the Drosophila larva. Immunostaining of the larval salivary gland localized myosin V to the nuclear envelope. It colocalized with Drosophila lamin C, a marker for the nuclear envelope. Immunoprecipitation experiments of larval extracts using lamin C antibody pulled down myosin V. Mutants of myosin V and over expression of myosin V in the larval salivary gland using the UAS-GAL4 system showed aberrant lamin C staining on the nuclear envelope. We are in the process of characterizing a more precise localization of myosin V in the nuclear envelope in order to postulate the role of myosin V in maintaining the structural integrity of the nuclear envelope in the salivary gland. The hemolymph of Drosophila contains hemocytes, which are cells that circulate through the body cavities. They are responsible for the phagocytosis of apoptotic cells. Hemocytes can also engulf and melanize foreign material in response to an infection. Immunostaining of larval hemocytes showed myosin V ubiquitously expressed in the cytoplasm with staining in some vesicles. In hemocytes with filopodia-like-protrusions, myosin V is seen in the protrusions and occasionally at the tip of the protrusions. Hemocytes isolated from a deletion mutant of myosin V displayed abnormal phenotypes. We are studying the role of myosin V in the larval hemocytes and identifying other myosin V interacting proteins that are expressed in the filopodia-like protrusions of the hemocytes.